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serenity/Userland/Libraries/LibThreading/BackgroundAction.h
kleines Filmröllchen 704bb361bb LibCore: Allow event loops on other threads to wake up
Because the wake pipe is thread-local, it was previously not possible
to wake an event loop across a thread. Therefore, this commit
rearchitects event loop waking by making the wake function a member of
the event loop itself and having it keep a pointer to its thread's wake
pipe. The global wake() function calls wake on the current thread's
event loop.

This also fixes a bug in BackgroundAction: it should wake the event loop
it was created on, instead of the current thread's event loop.
2022-02-13 23:06:53 +01:00

79 lines
1.9 KiB
C++

/*
* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Function.h>
#include <AK/NonnullRefPtr.h>
#include <AK/Optional.h>
#include <AK/Queue.h>
#include <LibCore/Event.h>
#include <LibCore/EventLoop.h>
#include <LibCore/Object.h>
#include <LibThreading/Thread.h>
namespace Threading {
template<typename Result>
class BackgroundAction;
class BackgroundActionBase {
template<typename Result>
friend class BackgroundAction;
private:
BackgroundActionBase() { }
static void enqueue_work(Function<void()>);
static Thread& background_thread();
};
template<typename Result>
class BackgroundAction final : public Core::Object
, private BackgroundActionBase {
C_OBJECT(BackgroundAction);
public:
void cancel()
{
m_cancelled = true;
}
bool is_cancelled() const
{
return m_cancelled;
}
virtual ~BackgroundAction() { }
private:
BackgroundAction(Function<Result(BackgroundAction&)> action, Function<void(Result)> on_complete)
: Core::Object(&background_thread())
, m_action(move(action))
, m_on_complete(move(on_complete))
{
enqueue_work([this, origin_event_loop = &Core::EventLoop::current()] {
m_result = m_action(*this);
if (m_on_complete) {
origin_event_loop->deferred_invoke([this] {
m_on_complete(m_result.release_value());
remove_from_parent();
});
origin_event_loop->wake();
} else {
this->remove_from_parent();
}
});
}
bool m_cancelled { false };
Function<Result(BackgroundAction&)> m_action;
Function<void(Result)> m_on_complete;
Optional<Result> m_result;
};
}